A javascript hack to have Spry CollapsiblePanels remember their state

Adobe Dreamweaver uses the Spry CollapsiblePanel plugin to create boxes that expand and collapse when a heading is clicked.

The following code allows the open/close state of the panels on a page to be remembered when the page is reloaded, or when history is accessed. It can also be used to share the open/close state between many pages containing the same panels.